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The ambient-pressure phase α of C4H2N5Cl transforms under 0.18 GPa to a higher-symmetry phase α′, but its high-pressure recrystallization below 0.20 GPa leads to a stochastic hydrate while above 0.20 GPa recrystallization leads to a new phase, β., Partial hydration of organic compounds can be achieved by high-pressure crystallization. This has been demonstrated for the high-nitro­gen-content compound 6-chloro-1,2,3,4-tetrazolo[1,5-b]pyridazine (C4H2N5Cl), which becomes partly hydrated by isochoric crystallizations below 0.15 GPa. This hydrate, C4H2N5Cl·xH2O, is isostructural with the ambient-pressure phase α of C4H2N5Cl, but the crystal volume is somewhat larger than that of the anhydrate. At 0.20 GPa, the α-C4H2N5Cl anhydrate phase transforms abruptly into a new higher-symmetry phase, α′; the transformation is clearly visible due to a strong contraction of the crystals. The hydrate α-C4H2N5Cl·xH2O can also be isothermally compressed up to 0.30 GPa before transforming to the α′-C4H2N5Cl·xH2O phase. The isochoric recrystallization of C4H2N5Cl above 0.18 GPa yields a new anhydrous phase β, which, on releasing pressure, transforms back to the α phase below 0.15 GPa. The structural transition from the α to the β phase is destructive for the single crystal and involves a large volume drop and significant elongation of all the shortest intermolecular distances which are the CH⋯N and CH⋯Cl hydrogen bonds, as well as the N⋯N contacts. The α-to-α′ phase transition increases the crystal symmetry in the subgroup relation; however, there are no structural nor symmetry relations between phases α and β.

Reaction of K8{Ta6O19}·16H2O with [Ni(tren)(H2O)Cl]Cl·H2O in different solvents led to the formation of single crystals of the title compound, [Ni4Ta6O19(C6H18N4)4]·19H2O or {[Ni2(κ4-tren)(μ-κ3-tren)]2Ta6O19}·19H2O (tren is N,N-bis(2-aminoethyl)-1,2-ethanediamine, C6H18N4). In its crystal structure, one Lindqvist-type anion {Ta6O19}8– (point group symmetry \overline{1}) is connected to two NiII cations, with both of them coordinated by one tren ligand into discrete units. Both NiII cations are sixfold coordinated by O atoms of the anion and N atoms of the organic ligand, resulting in slightly distorted [NiON5] octahedra for one and [NiO3N3] octahedra for the other cation. These clusters are linked by intermolecular O—H...O and N—H...O hydrogen bonding involving water molecules into layers parallel to the bc plane. Some of these water molecules are positionally disordered and were refined using a split model. Powder X-ray diffraction revealed that a pure crystalline phase was obtained but that on storage at room-temperature this compound decomposed because of the loss of crystal water molecules.

The metal ion of the title salt hydrate shows a 4 + 2 (N4O2) tetra­gonally elongated coordination geometry defined by four macrocyclic-N atoms and two weakly associated acetate-O atoms; the crystal features conventional hydrogen-bonding inter­actions., The title CuII macrocyclic complex salt tetra­hydrate, [Cu(C22H46N6O2)](C2H3O2)2·4H2O, sees the metal atom located on a centre of inversion and coordinated within a 4 + 2 (N4O2) tetra­gonally distorted coordination geometry; the N atoms are derived from the macrocycle and the O atoms from weakly associated [3.2048 (15) Å] acetate anions. Further stability to the three-ion aggregate is provided by intra­molecular amine-N—H⋯O(carboxyl­ate) hydrogen bonds. Hydrogen bonding is also prominent in the mol­ecular packing with amide-N—H⋯O(amide) inter­actions, leading to eight-membered {⋯HNCO}2 synthons, amide-N—H⋯O(water), water-O—H⋯O(carboxyl­ate) and water-O—H⋯O(water) hydrogen bonds featuring within the three-dimensional architecture. The calculated Hirshfeld surfaces for the individual components of the asymmetric unit differentiate the water mol­ecules owing to their distinctive supra­molecular association. For each of the anion and cation, H⋯H contacts predominate (50.7 and 65.2%, respectively) followed by H⋯O/O⋯H contacts (44.5 and 29.9%, respectively).

Although the wettability of hydrate surfaces and hydrate film growth are key to understanding hydrate agglomeration and pipeline plugging, a quantitative understanding of the coupled behavior between both phenomena is lacking. In situ measurements of wettability coupled with film growth were performed for cyclopentane hydrate surfaces in cyclopentane at atmospheric pressure and temperatures between 1.5-6.8 °C. Results were obtained as a function of annealing (conversion) time and subcooling. Hydrate surface wettability decreased as annealing time increased, while hydrate film growth rate was unaffected by annealing time at any subcooling. The results are interpreted as a manifestation of the hydrate surface porosity, which depends on annealing time and controls water spreading on the hydrate surface. The wettability generally decreased as the subcooling increased because higher subcooling yields rougher hydrate surfaces, making it harder for water to spread. However, this effect is balanced by hydrate growth rates, which increase with subcooling. Also affecting the results, surface heating from heat release (from exothermic crystallization) allows excess surface water to promote spreading. The hydrate film growth rate on water droplets increased with subcooling, as expected from a higher driving force. At any subcooling, the instantaneous hydrate growth rate decreased over time, likely from heat transfer limitations. A new phenomenon was observed, where the angle at the three-phase point increases from the initial contact angle upon hydrate film growth, named the crystallization angle. This is attributed to the water droplet trying to spread while the thin film is weak enough to be redirected. Once the hydrate film grows and forms a "wall" around the droplet, it cannot be moved, and further growth yields a crater on the droplet surface, attributed to water penetrating the hydrate surface pore structures. This fundamental behavior has many flow assurance implications since it affects the interactions between the agglomerating hydrate particles and water droplets.

In this work, ammonia intercalated zinc hydroxide chloride hydrate (ZHC-NH3), Zn5(OH)8Cl2.4[(H2O)x(NH3)1-x)] was synthesised using precursor, [ZnCl2.2{HONC(CH3)2}] by sol-gel method in presence of ...

Clarifying the effect of asphaltene on hydrate formation and growth is of great significance to the operation safety in deepwater petroleum fields. To investigate the influence of low-concentration dissolved asphaltenes on the formation kinetics and growth process of hydrates in water-in-oil emulsions, experiments with asphaltene concentrations ranging from 50 to 1000 ppm were carried out using a high-pressure visual reactor. At a low concentration, the adsorption of asphaltene monomers on the oil-water interface or nanoaggregates in the bulk barely affected the nucleation of hydrate and the induction time of hydrate formation. However, it would hinder the microscopic mass transfer process and heat transfer process between gas molecules and then mitigate the initial rate of hydrate formation. Therefore, the dissolved asphaltenes could not be used as antiagglomerants (AAs) to efficiently inhibit the aggregation of hydrate particles at low concentrations under our experimental conditions, causing extensive hydrate agglomeration and deposition in the reactor.

The gas hydrates' ability to preferentially bind one of the components of a gas mixture into a hydrate state makes it possible to consider hydrate-based technology as promising for the separation of gas mixtures. When a hydrate is obtained from a gas mixture, mixed hydrates with a complex composition inevitably occur. Issue of their composition determination stays apart. This a rather difficult task, which is complicated by the dissolution of small molecules such as hydrogen in the hydrate phase. This, in turn, impedes the analysis of the data obtained. In this work, the solubility of hydrogen in carbon dioxide hydrate in the range of 269.7–275.7 K and at partial H2 pressure up to 4.5 MPa was experimentally determined. Hydrate composition was found to be CO2·(0.01X)H2·6.5H2O at H2 pressure of X MPa. The equilibrium conditions of hydrates formation in the systems of H2O – CO2 – H2 and H2O – 2-propanol – CO2 – H2 were also determined in a wide range of hydrogen concentrations. Hydrogen seems to be an indifferent diluent gas regarding CO2 hydrate equilibrium pressure. The compositions of the equilibrium phases have been determined as well. It was shown that isopropanol does not form a double hydrate with СО2, only sI СО2 hydrate occurred in the studied systems. The obtained dependencies will be useful in analyzing the process of СО2 + Н2 gas mixtures separation by the hydrate-based method.

The title coordination polymer, {[Co2(C12H7NO8)(H2O)6]·5H2O} n , was crystallized at room temperature from an aqueous solution of 2-aminodiacetic terephthalic acid (H4adtp) and cobalt(II) nitrate. The asymmetric unit consists of one adtp4− ligand, one and two half CoII ions, six water ligands coordinated to CoII ions and five uncoordinated water molecules. Two of the cobalt cations lie on centres of inversion and are coordinated in octahedral O2(OH2)4 environments, whereas the other adopts a slightly distorted octahedral NO3(OH2)2 environment. The crystal structure contains parallel stacked, one-dimensional zigzag chains, {[Co2(C12H7NO8)(H2O)6]} n , which assemble into a three-dimensional supramolecular architecture via networks of hydrogen bonds involving the coordinated and free water molecules. One-dimensional `water tapes' are formed, containing alternating six-membered and twelve-membered rings of water molecules, together with water pentamers, in which a central uncoordinated water molecule is hydrogen bonded to two coordinated and two free water molecules in a tetrahedral arrangement.

The asymmetric unit of the polymeric title compound {[Co2(C12H7NO8)(H2O)2]·1.6H2O} n comprises two CoII ions, which are coordinated by fully deprotonated 2-aminodiacetic terephthalic acid (adtp4–) and terminal water molecules in distorted octahedral N1O5 and O6 coordination environments. The title compound features tetranuclear CoII units bridged by κ 3 O:O:O′- and κ 3 O:O,O′-carboxylate groups, which are joined into ribbons via syn–anti carboxylate bridges. The parallel adtp4– ligands with an alternately reversed arrangement further link adjacent CoII ribbons into (010) layers, which are assembled into a three-dimensional supramolecular network via intermolecular hydrogen bonds. The disordered water solvent molecules are situated in channels parallel to [100]. Magnetic measurements and analyses reveal that the title compound displays antiferromagnetic behaviour. The purity of the title compound was characterized by X-ray powder diffraction.

An understanding of the structure–properties relationship of crystals is one of the principles of crystal engineering. It is well established that the physicochemical properties of solids, such as ...

Ti3+/N-co-doped TiO2 was successfully synthesized in situ by one-step hydrothermal method using tetrabutyl titanate (TBOT) as the titanium source and hydrazine hydrate as the reducing agent and nitrogen source. Afterward, the microstructure and physicochemical properties of the catalysts were characterized by transmission electron microscopy, X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, UV–vis diffuse reflectance spectroscopy, and photoluminescence spectroscopy. Results indicated that nitrogen was effectively doped into the lattice of TiO2 and Ti3+ was stably presented in the prepared TiO2, which reduced the band-gap TiO2 (2.96–2.75 eV) and enhanced photo-induced charge separation efficiency under visible light. In addition, the photocatalytic activity was evaluated by degradation of rhodamine B under xenon lamp with 420 nm filter. With the amount of hydrazine hydrate increased, the photocatalytic degradation performance of the sample increased first and then decreased. When the volume ratio of hydrazine hydrate to TBOT was 1:5, the sample showed the best photocatalytic performance.

One of the long-standing challenges in working with organic hydrates in general, and channel hydrates in particular, is their propensity to lose water over time and convert (either partially or ful...

An effective and rapid method for the detection of hydrazine hydrate is urgently needed as a result of its high toxicity and extensive use. Here, copper nanoparticles supported on carbon (written as: Cu NP/C) and copper oxide polycrystalline solids (written as: CuO PS), synthesized by calcining the same metal–organic framework at high temperature, were respectively used as electrode materials for electrochemical sensing hydrazine. The results show that the prepared Cu NP/C exhibits a better performance with a sensitivity of 0.1726 mA (mmol/L)−1, a wider linear range of 0.1–2.4 mM and a lower detection limit of 0.0014 mmol·L−1, compared to the obtained CuO PS. This can be reasonably explained by the lower copper valence state and its interaction with the carbon supports in Cu NP/C. Furthermore, the good selectivity and anti‐interference ability from the Cu NP/C are also acquired for electrochemical detection of hydrazine.

The aim of this paper is to establish the optimal content of carbon material in composites with nanocrystal hydrate nickel molybdate. To achieve this, NiMoO4 / C composites with a carbon material content of 1, 5 and 10% by weight (with and without ultrasonic irradiation) were obtained by hydrothermal method. As a result of electrochemical studies, it was found that the maximum specific capacitance of 628 F/g is reached by a composite with a carbon content of 1% after ultrasonic exposure, while this composite shows excellent electrical conductivity, which is 0.47 Ohm-1m-1.

The temperature field of a methane hydrate in the process of its decomposition at a closed-room temperature was investigated with the use of a special-purpose experimental setup. The results obtained are expected to be useful for the storage and transportation of gas hydrates.

Results of numerical investigation of the injection of liquid carbon dioxide into a porous stratum saturated with methane and its gas hydrate, accompanied by the replacement of methane in the methane gas hydrate by carbon dioxide, are presented. A round stratum with an impermeable outer boundary of finite radius was considered. It was established that, depending on the duration of the injection of liquid carbon dioxide into such a stratum, the replacement of methane in the methane gas hydrate by carbon dioxide can proceed with the boiling of carbon dioxide or without it.

In the crystal, mol­ecules are linked by pairs of N—H⋯O hydrogen bonds into ribbons along the c-axis direction. The layered crystal packing is further consolidated by van der Waals and C—H⋯π inter­actions., In the crystal, the whole mol­ecule of the title compound, C14H12N4O7·0.224H2O, is nearly planar with a maximum deviation from the least-squares plane of 0.352 (1) Å. The mol­ecular conformation is stabilized by an intra­molecular N—H⋯O hydrogen bond, generating an S(6) ring motif. In the crystal, mol­ecules are linked by centrosymmetric pairs of N—H⋯O hydrogen bonds, forming ribbons along the c-axis direction. These ribbons connected by van der Waals contacts, forming sheets parallel to the ac plane. There are also inter­molecular van der Waals contacts and and C—H⋯π inter­actions between the sheets. A Hirshfeld surface analysis indicates that the most prevalent inter­actions are O⋯H/H⋯O (41.2%), H⋯H (19.2%), C⋯H/H⋯C (12.2%) and C⋯O/ O⋯C (8.4%).

X-ray crystallography on [EtOC(=O)N(H)C(=N+H2)NH2]Cl·½H2O (1) shows the asymmetric unit to comprise two independent cations, two chloride anions and crystal water. The main conformational difference between the cations is seen in the relative orientation of the ethyl groups; geometry-optimisation confirms the all-trans conformation is the most stable. The remaining parts of the cations are co-planar and feature intramolecular N–H···O(carbonyl) hydrogen bonds. An analysis of the C–N bonds suggests substantial delocalisation of the positive charge over the CN3 atoms. In the crystal, columns comprising the first independent cation are surrounded by four columns of the second cation within a network of water-O–H···Cl, N–H···Cl and N–H···O(water, carbonyl) hydrogen bonds, many of which are charge-assisted. The packing has been further investigated by Hirshfeld surface analysis, molecular electrostatic potential and interaction energy calculations. The charge-assisted N–H···Cl hydrogen bonds are significantly stronger than the water-O–H···Cl interactions consistent the distribution of the positive charge over the CN3 atoms.

Compound 1-(3-amino-4-morpholino-1H-indazole-1-carbonyl)-N-(4-methoxyphenyl)cyclopropane-1-carboxamide (C22H23N5O3, Mr = 870.96) was synthesized by condensation of 1-(4-methoxyphenylcarbamoyl)cyclopropane-1-carboxylic acid with 4-morpholino-1H-indazol-3-amine, which was prepared from 2,6-difluorobenzonitrile by amination with morpholine and subsequent cyclization with hydrazine hydrate. The crystal structure was determined. The results of biological activity determination indicated that the compound exhibited significant inhibitory activity against some cancer cell lines.

The crystal structure of the novel hydrated CuII salt, [Cu(L)(H2O)2]Cl2·4H2O (L = 3,14-diethyl-2,6,13,17-tetraazatricyclo[16.4.0.07,12]docosane, C22H44N4) has been determined using synchrotron radiation. The asymmetric unit contains one half of the [Cu(L)(H2O)2]2+ cation (completed by crystallographic inversion symmetry), one chloride anion and two lattice water molecules. The copper(II) atom exists in a tetragonally distorted octahedral environment with the four N atoms of the macrocyclic ligand in equatorial and two O atoms from water molecules in axial positions. The latter exhibit a long axial Cu—O bond length of 2.7866 (16) Å due to the Jahn–Teller distortion. The macrocyclic ring adopts a stable trans-III conformation with typical Cu—N bond lengths of 2.0240 (11) and 2.0441 (3) Å. The complex is stabilized by hydrogen bonds formed between the O atoms of coordinated water molecules and the NH groups as donors, and chloride anions as acceptors. The chloride anions are further connected to the lattice water solvent molecules through O—H...Cl hydrogen bonds, giving rise to a three-dimensional network structure.

The crystal structure of the title salt, C20H42N4 2+·2ClO4 −, has been determined using synchrotron radiation at 220 (2) K. The structure determination reveals that protonation has occurred at diagonally opposite amine N atoms. The asymmetric unit comprises one half of the organic dication, which lies about a center of inversion, and one perchlorate anion. The macrocyclic dication adopts the most stable endodentate trans-III conformation. The crystal structure is stabilized by intramolecular N—H...N, and intermolecular N—H...O and C–H...O hydrogen bonds involving the macrocycle N—H and C—H groups as donors and the O atoms of perchlorate anions as acceptors, giving rise to a three-dimensional network.

Using hydrazine hydrate (N2H4·H2O) as precipitant, micro-flowers NiWO4 was prepared by co-precipitation and low-temperature heat treatment, and its capacitance was studied. The different amount of N2H4·H2O resulted in two different morphologies of the samples. The electrochemical performance of the sample was tested by CV, GCD, and EIS. The results show that the specific capacitance of the nickel tungstate electrode is 170 F g−1 when the current density is 1 A g−1 in 6 M KOH solution, and the specific capacitance and rate performance of the sample are greatly improved.

Hydrate flow obstacles encountered during the exploitation of deep-water gas fields has received an increased attention. Based on the variations in the wellbore temperature of a deep-water gas well during the initial restarting period, and considering the interrelationship between the hydrate behavior and heat transfer, a prediction model for hydrate flow obstacle was established by comprehensively considering the hydrate formation, deposition, and decomposition. This model could be used to analyze the hydrate formation and decomposition regions dynamically and depict the evolution of the hydrate plug quantitatively during the restarting period. The computation results demonstrated that the wellbore temperature increased with the restarting time, which caused the hydrate formation region to decrease accordingly. During the initial restart under testing operations, hydrates always formed at low gas production rates in the tubing, which could plug the tubing after a certain restarting time. The risk of hydrate flow obstacle first increased and then decreased with an increase in the restarting production rate. During the initial restart under production operations, hydrates only formed at the initial restarting stage, which ranged from several minutes to more than 10 h. The hydrate flow obstacle risk first increased and then decreased with the restarting time, and no hydrate plugging occurred during the initial restarting period of the entire production process. Finally, the measures for preventing hydrate plugging during the initial restarting period were discussed. This work provides a valuable theoretical reference for preventing hydrate plugging during the initial restarting period of a deep-water gas well.

This paper reports the formation and dissociation pattern of hydrate crystals with varying compositions of CH4 and CO2 in porous media. Direct visualization was carried out using a high-pressure, water-wet, silicon wafer-based micromodel with a pore network resembling sandstone rock. Hydrate crystals were formed under reservoir conditions (P = 45–65 bar and T = 1.7–3.5 °C) from either a two-phase system consisting of liquid water and a CH4–CO2 gas mixture or a three-phase system consisting of liquid water, CH4-rich gas, and CO2-rich liquid. A stepwise pressure reduction method was later applied to visualize multiple dissociation events occurring between the equilibrium pressures of pure CH4 hydrates and pure CO2 hydrates. The results showed that liberated gas from the initial dissociation became trapped and immobilized by surrounding undissociated hydrate crystals when the initial hydrate saturation was high. Mixing of liberated gas with liquid water led to rapid reformation of hydrates during the stepwise pressure reduction; the reformed hydrate crystals dissociated at a lower pressure close to the equilibrium pressure of pure CO2 hydrates. The results demonstrate the possibility of producing gas liberated from local hydrate dissociation while simultaneously reforming hydrates in other parts of the sediments. This is relevant for the proposed production method where CO2 injection in CH4 hydrate reservoirs is followed by pressure depletion to enhance the CH4 gas recovery.

sH hydrate is a kind of hydrate that is consisted of only organic large molecule and water. Since each organic large molecule can bring five small cages that easily capture hydrogen molecules, sH hydrate is potential hydrogen storage material. In this paper, methylcyclohexane-hydrogen hydrate was used for hydrogen storage. Two different processes, the simultaneous formation and the induced formation, were studied by molecular dynamics simulation. The simultaneous formations of methylcyclohexane-hydrogen binary hydrate were simulated at 230 K & 110 MPa and the hydrogen storage capacity of binary hydrate was 1.08 wt%. The induced formation of methylcyclohexane-hydrogen binary hydrate was simulated at 240–260 K &20–110 MPa.The simulation results showed that hydrogen storage capacity of hydrate was mainly affected by temperature. The hydrogen storage capacity of hydrates was low (≤1.0 wt%) at 250–260 K even the pressure increased to 110 MPa. While the hydrogen storage capacity was greatly improved (≥1.6 wt%) at 240 K. At 250–260 K, hydrogen molecules only entered the cavities that were near the interface, which seems that 512 cages layers obstructed the hydrogen molecules. The results indicated that the induced hydrogen formation required milder conditions than the simultaneously hydrogen storage formation, and the hydrogen storage was higher.

Poly(N-vinylamide) derivatives were synthesized to improve the performance of kinetic hydrate inhibitors (KHIs). In this work, we synthesized poly(N-vinylformamide) (PNVF) and poly(N-vinylcaprolactam) (PVCap) by free radical polymerization with several commercial chain transfer agents (CTAs), which afforded a few thousand Mn. The structures of synthesized PNVF and PVCap were then investigated by 1H NMR and MALDI-TOF/MS spectrograms. KHI properties of the synthesized PNVF and PVCap polymers were also evaluated by the high-pressure slow constant cooling KHI test method. Some of the tested polymers showed a better KHI effect than PVCap.

A study on the hydration behavior of fluconazole demonstrates that both sample age and polymorphic form impact the drug’s kinetic stability to hydration. For two of the polymorphs, aged samples wer...

Nevirapine (NEV) is an antiretroviral drug which falls under the Biopharmaceutics Classification System (BCS) class II category. In this work, we report the synthesis of new eutectic and cocrystal ...

We have obtained nanocrystalline hydrate and alpha phase of nickel molybdate by a hydrothermal technique. On the basis of the obtained cyclic voltammetry data, we have evaluated the contribution of faradaic and non-faradaic processes to the total capacitance of molybdates under study. It was found that the specific capacitance of hydrate NiMoO4·H2O is 621 F/g at a scan rate of 1 mV / s and the specific capacitance of the α-NiMoO4 is 281 F/g. Cathodes for hybrid supercapacitors were formed on the basis of the obtained nickel molybdates. As a result of electrochemical studies, it was found that the specific capacitance of hybrid supercapacitor based on NiMoO4·H2O/C was 256 F/g at the current of 0.2 A/g, while the specific energy was 80 W h/kg and specific power – 304 W/kg and these results are higher below in the α-NiMoO4 /C-based hybrid supercapacitor.

C19H18O7, orthorhombic, P21212 (no. 18), a = 12.467(3) Å, b = 39.168(8) Å, c = 7.6005(16) Å, V = 3711.4(14) Å3, Z = 4, R gt (F) = 0.0440, wR ref (F 2) = 0.1054, T = 296.15 K.

With the aid of the confined conversion of layered silicate RUB-15, homogeneously dispersed Au and SnO2 nanoparticles (NPs) were generated in the confined layer space of RUB-15. The Au-SnO2/SiO2 composite was obtained with the structure that ultrafine Au and SnO2 NPs were supported on SiO2 lamellas. Benefited by the Sn(II)-assisted in situ reduction strategy, Au NPs were highly uniformed and evenly distributed in/on the RUB-15. This Au-SnO2/SiO2 composite was employed as a catalyst to the reduction of 4-nitrophenol showing excellent catalytic activity. The catalytic rate constant at room temperature was calculated to be 6.64 min-1, which was dramatically higher than that of Au/SiO2 composite produced by reduction with hydrazine hydrate on the same support of layered silicate RUB-15. The interaction between Au and SnO2 NPs increased the electron density around Au NPs, which was demonstrated to be an essential factor to the excellent catalytic activity of the Au-SnO2/SiO2 composite. The simple and universal synthesis method afforded precise control over the size/spatial arrangement of Au and SnO2 NPs on SiO2 lamellas. The high activity of the Au-SnO2/SiO2 composite demonstrated that the strategy used in this study has good potential application prospect. Furthermore, this work provided new perspective on the catalysis mechanism to the metal/semiconductor synergistic catalyst system.

The structures of the di­methyl­ated versions of two natural products found in toad secretions, bufotenine and bufotenidine, are reported, as well as the hydrate of 2,5-di­methyl­bufotenidine., The solid-state structure of the bufotenine derivative bis­(5-meth­oxy-2,N,N-tri­methyl­tryptammonium) (5-MeO-2-Me-DMT) fumarate (systematic name: bis­{[2-(5-meth­oxy-2-methyl-1H-indol-3-yl)eth­yl]di­methyl­aza­nium} (2E)-but-2-enedioate), 2C14H21N2O+·C4H2O4 2−, the bufotenidine derivative 5-meth­oxy-2,N,N,N-tetra­methyl­tryptammonium (5-MeO-2-Me-TMT) iodide {systematic name: [2-(5-meth­oxy-2-methyl-1H-indol-3-yl)eth­yl]tri­methyl­aza­nium iodide}, C15H23N2O+·I−, and the hydrate of the same {systematic name: [2-(5-meth­oxy-2-methyl-1H-indol-3-yl)eth­yl]tri­methyl­aza­nium iodide monohydrate}, C15H23N2O+·I−·H2O, are reported. The structure of 5-MeO-2-Me-DMT fumarate possesses one tryptammonium cation and a half of a fumarate dianion in the asymmetric unit, linked together by N—H⋯O hydrogen bonds in infinite two-dimensional networks parallel to the (101) plane. The structure of 5-MeO-2-Me-TMT iodide possesses one tryptammonium cation and one iodide anion in the asymmetric unit. The ions are linked via N—H⋯I hydrogen bonds, and indoles are coupled in dimers through π–π inter­actions. The hydrate of 5-MeO-2-Me-TMT iodide possesses one tryptammonium cation, one iodide anion and one water mol­ecule in the asymmetric unit. It shows N—H⋯I and O—H⋯I hydrogen bonds that couple the tryptammonium cations into dimers.

Herein, two new Co(II) CPs, {[Co(H3L)(bpa)]·H2O}n (1) and {[Co2(H3L)2(phen)2(H2O)2]·3H2O}n (2) were hydrothermally obtained based on O-donor semi-rigid polycarboxylic acid ligand H5L (5,5’-((5-carboxy-1,3-phenylene)bis(oxy))diisophthalic acid) and N-donor coligands, such as bpa (1,2-bis(4-pyridyl)ethane), phen (1,10-phenanthroline hydrate). Both of them were studied by single crystal X-ray diffraction analysis, thermogravimetric analysis, infrared spectra, powder X-ray diffraction and variable-temperature magnetic susceptibilities. CP 1 features a one-dimensional chain, further stacked to a two-dimensional layer and three-dimensional structure through π···π stacking interactions and hydrogen bonds. CP 2 displays two-dimensional layers, which further extended into three-dimensional frameworks through C−H···π interactions and hydrogen bonds. In addition, variable-temperature magnetic susceptibility data were investigated, indicating that the CPs 1 and 2 exhibited antiferromagnetic interactions.

The formation of a self-interpenetrated honeycomb molecular network based upon 4,6-dichlororesorcinol (4,6-diCl res), a water molecule, and the photoproduct rtct-tetrakis(pyridin-4-yl)cyclobutane ( rtct -TPCB) is reported. Interestingly, only three of the four pyridine rings on the central cyclobutane ring are found to engage in O—H...N hydrogen bonds with either the 4,6-diCl res or an included water molecule, resulting in a three-connected net. Notably, the solid (4,6-diCl res)·( rtct -TPCB)·(H2O), C6H4Cl2O2·C24H20N4·H2O, contains channels that run along the crystallographic b axis, which are found to be interpenetrated. Although rtct -TPCB has been employed as a bridging ligand in the formation of numerous metal–organic materials, surprisingly neither the single-component X-ray structure nor any multi-component molecular solids based upon this stereoisomer have been reported previously. Lastly, the single-crystal X-ray structure of the photoproduct rtct -TPCB is also reported.

The dynamic combinatorial library (DCL) of cyamelurates consists of 17 tautomers of cyameluric acid and their ions, as well as metal aqua complexes. That leads to a variety of compounds in the Zn(NO3)2 – K3(C6N7O3) – H2O system. All compounds are obtained with impurity amorphous and crystalline phases, which complicates their study. In this work, metastable phases of zinc, nickel, and iron cyamelurates were obtained and their crystal structures were determined for the first time. Kinetic control of chemical reactions allowed us to isolate two zinc cyamelurate metastable phases. The metastable compound K2Zn(C6N7O3H)2∙8H2O is formed immediately after mixing the precursor solutions, and after two hours, it is converted to another metastable compound Zn(C6N7O3H)∙5H2O. Due to hydrate isomerization, after 12 hours in the mother liquor, the latter transforms into a thermodynamically stable compound of the same composition. The features of the synthesis and crystalline structure of zinc cyamelurates can be interpreted from the standpoint of the nonclassical nucleation theory. The crystal structures of the synthesized compounds K2Zn(C6N7O3H)2∙8H2O, Zn(C6N7O3H)∙5H2O, and Zn(C6N7O3H2)2∙8H2O allowed us to conclude that decomposition of supersaturated zinc solution leads to the formation of double electric micelles (DEM). They can be considered nanoreactors playing an important role in crystal nucleation.

The limited applications of α-cyclodextrin (αCD) require elaboration of effective preparation procedures for inclusion compounds of this native macrocyclic host. The solid-phase guest exchange in anhydrous inclusion compounds with organic guests was used in the present work to activate the inclusion properties of αCD without the presence of water. The initial inclusion compounds and the products of this exchange process were characterized using thermogravimetry combined with mass spectrometry of evolved vapors (TG/MS) and powder X-ray diffraction. Solid-phase guest exchange in inclusion compounds of αCD enables encapsulation of organic guests in the higher amounts than can be achieved with a saturated hydrate of α-cyclodextrin under the same conditions. The developed guest exchange procedure does not demand optimization of components ratio and preparation conditions. The solid-phase guest exchange in one of the studied ternary systems produces an amorphous inclusion compound, which heating gives a true amorphous αCD without any traces of its crystalline phase. This is a first evidence of α-cyclodextrin amorphization without its complete dissolution, that can be used in practical applications where an amorphous state of this host is needed having a higher inclusion capacity than its crystalline forms.

Herein, we report one-step approach for gram-scale synthesis of reduced graphene oxide (RGO) fine powder. Glucose as a precursor combined with chemical reagent/s has been hydrothermally treated to obtain RGO in gram-scale. Few milliliters of ammonia, ammonia-hydrazine hydrate mixture, NaOH or HCl were introduced to the reaction medium with glucose. It was found that the number of H+ protons produced from the evolved byproduct hydrogen gas has a vital role in deoxygenating the aromatic sp2 domains constituting the graphitic structure. Besides, the evolved nitrogen gas produced from ammonia and ammonia-hydrazine creates a fitted inert atmosphere to cope with any oxygenation process. Accordingly, graphitic powder resulted from the addition of ammonia-hydrazine mixture, Amm-Hyz-RGO, represents the RGO sample of the best structural quality and best structural order interior of the aromatic sp2 domains. Moreover, flat nanoplatelets morphology has been confirmed for both Amm-Hyz-RGO and the graphitic sample resulted from addition of ammonia, Amm-RGO. The quality of Amm-RGO is nearby to that of the Amm-Hyz-RGO. However, Amm-RGO formed significantly in larger yield than Amm-Hyz-RGO. Accordingly, Amm-RGO is considered to be the optimum sample, regarding the quality as well as the productivity.

Dietary supplementation is prevalent in our daily life, in which tablet form plays an important role due to its long-term stability and cost-effectiveness. In the pharmaceutical industry, coordination polymer-based tablets are widely produced for dietary supplementation. The mechanical properties of such dietary supplements are very crucial for the tableting process and need to be broadly studied. In this study, the mechanical properties of a copper supplement, namely copper glycinate hydrate (Cu[O2CCH2NH2]2·H2O), have been studied via high-pressure synchrotron powder X-ray diffraction and density functional theory calculations. This material is a 1D coordination polymer, and adjacent chains are linked via hydrogen bonding in the structure. The measured bulk modulus (Ko) is ∼13.9 GPa, which is comparable to that of small organic drug crystals and far smaller than that of inorganic dietary supplements. The calculated Young's moduli (13.55–35.75 GPa) indicate a significant elastic anisotropy, and the directional dependent Young's modulus can be substantiated with the underlying atomic structure. Our experimental and calculated results provide useful quantitative information for tableting and formulating this dietary supplement in the pharmaceutical industry.

A jumping crystal of the channel-type hydrate of spironolactone–saccharin cocrystals was presented as the first example of a crystal that jumps without changes in both the lattice constant and the molecular conformation, emphasizing the general applicability of our newly proposed design concept that introduces an easy-to-escape component, the jumping-mate, to generate crystal motions.

Isavuconazole (ISV) is a systemic antifungal agent which is used to treat invasive aspergillosis, mucormicosis and candidiasis. Although both oral and intravenous dosage forms of this drug exist on the market, the crystal structure and physicochemical properties of ISV as well as possible alternative solid forms are yet unexplored in the literature. In the present work, the solid form landscape of isavuconazole including solvate, polymorph and salt screening was studied systematically. The solid-state properties of initial crystalline ISV and newly obtained forms (ISV monohydrate, two amorphous forms obtained by different means and two pharmaceutical salts with p-toluenesulfonic and phosphoric acids) were described for the first time. The structures of all crystalline forms were solved based on the single crystal X-Ray diffraction data, and the packing forces in the considered solids were studied using different theoretical approaches. The transformation pathways between the ISV solid forms were investigated experimentally and rationalized based on the DFT computations and non-covalent interaction analysis. It was observed that crystalline isavuconazole does not transform into the hydrate upon dissolution, in contrast to other solid forms. The amorphous and salt forms of ISV were found to demonstrate a spring-like increase of the drug concentration in pharmaceutically relevant buffer media. The tableting of the pharmaceutical salts leads to slower phase transformation into the ISV hydrate and prolonged drug supersaturation.

As one of the most ubiquitous biominerals, calcium oxalate (CaOx) exhibits different hydrate phases. Although the monohydrate (whewellite, COM) is the thermodynamically favorable phase at ambient temperatures, the metastable dihydrate (weddellite, COD) can still stably exist in pathological mineralization but the stabilization mechanisms remain unclear. Herein, the in situ phase transformation of nano-sized COD to COM in the presence of citrate (CA) and zinc ions (Zn2+) as stabilizers was observed by time-resolved atomic force microscopy (AFM) and Raman spectroscopy. By a combination of zeta potential measurement, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), we demonstrate that CA can form a protective layer on the surface of nano-sized COD crystals to inhibit aggregation and delay the phase transformation of COD to COM. Due to the stabilizing/destabilizing effect of CA on the specific faces of COD, atypical-shaped COD crystals form. In addition, Zn2+ can substitute Ca2+ sites within the COD unit cell, shrinking the COD structure by compressing the “zeolite-like” channels to reduce weakly-bonded interchannel H2O molecules. This generates relatively smaller and more stable COD crystals with a typical pyramid shape to further retard COM formation. The obtained results provide new insights into modulating the stability of the metastable CaOx phases for potential control over pathological mineralization.

In the present study, we have described the synthesis and characterisation of the theophylline hydrate (Theo hydrate), cocrystal (Theo–Phen·2H2O) and hydrated sodium co-crystal of theophylline (Na–(Theo)2ClO·2H2O), where Theo = theophylline and Phen = 1,10-phenathroline. SC-XRD characterisation revealed strong interactions such as N⋯H⋯O, CO⋯H and C–H⋯π within the crystal structures. Studies revealed that Na–(Theo)2ClO·2H2O presented higher thermal stability (in the solid form) and improved solubility (when in contact with a polar solvent). The detailed analyses of Hirshfeld surface and fingerprint plots provided insight into the nature of non-covalent interactions in the compounds. In the case of Na–(Theo)2ClO·2H2O, solubility measurements indicated that Theo's solubility in water increases by a magnitude of four with respect to pure Theo. Biological studies showed that the high solubility of Theo as well as ClO4− is responsible for the distinct capabilities to inhibit the growth of different microorganisms, including Gram-positive (Staphylococcus epidermidis) and Gram-negative (Acinetobacter baumannii, Escherichia coli and Klebsiella pneumoniae) bacteria and fungi (Candida albicans and Candida tropicalis). Our results pointed out that cocrystals containing theophylline–phenanthroline can be explored to get promising molecules to be used to combat infections caused by clinically relevant (multi)drug-resistant bacteria and fungi.

The structure of a nickel(II) terephthalate complex, viz. tetra­aqua­bis­(pyridine-3-carbo­nitrile)­nickel(II) benzene-1,4-di­carboxyl­ate tetra­hydrate is described., A nickel(II) terephthalate complex, viz. [Ni(C6H4N2)2(H2O)4](O2CC6H4CO2)·4H2O, has been synthesized and studied by single-crystal X-ray diffraction. It crystallizes in the triclinic space group P . The crystal structure shows an approximately octa­hedral coordination environment of the complex with the [Ni(H2O)4(3-NCpy)2]2+ (3-NCpy is pyridine-3-carbo­nitrile) cation associated with four free water mol­ecules and hydrogen bonded to a terephthalate dianion [graph set R 2 2(8)]. The supra­molecular structure of the compound is stabilized by a three-dimensional array of O—H⋯O and O—H⋯N hydrogen bonds, along with π–π stacked pyridine-3-carbo­nitrile rings and C—H⋯O inter­actions.

It remains a difficult task to predict the hydrate structure and conformation of potential guest molecules in one of the three canonical hydrate lattices. 1-Pentanol is characteristic of molecules that lie at the margin of suitability as a guest molecule for the structure II hydrate phase, both because of its size and the presence of a hydrophilic OH group that tends to destabilize the clathrate hydrate framework. To manage the destabilizing influence of guest–host hydrogen bonding, some years ago a more robust framework was developed by doping the hydrate with NH₄⁺ and F⁻ ions in order to direct the guest hydrophilic groups away from the cage water molecules. Attempts to enclathrate 1-pentanol in the NH₄F doped clathrate were successful, but, surprisingly, the clathrate, as determined by PXRD, proved to be structure II (sII), even though the 1-pentanol appears to be too large to fit the pseudo-spherical 5¹²6⁴ cage. This suggested that the doped clathrate not only managed the guest–host hydrogen bonding network, but also forced the guest into a very compact conformation to fit the pseudospherical sII large cage (5¹²6⁴). These features were investigated further with ¹³C NMR and molecular dynamics simulations to identify the most likely guest conformation of 1-pentanol in the sII large cage.

The structural transition behaviors of the hydration and dehydration of mequitazine glycolate (MQZ–GLC) after exposure to heat and relative humidity have yet not been clarified, although our previous study demonstrated that mequitazine can be hydrated with glycolic acid. In this study, the hydration and dehydration behavior of MQZ–GLC were investigated using crystal structure analysis and water adsorption/desorption measurements. Dynamic vapor sorption measurements revealed that the MQZ–GLC anhydrate undergoes irreversible hydration above a certain humidity level. The crystal structure of the anhydrate was identified via structural analysis using in situ powder diffraction (PXRD) measurements and dispersion-corrected density functional theory (DFT-D) calculations. The structural characterization of the hydrate/anhydrate of MQZ–GLC showed that the formation of a hydrogen-bonding network by bridging crystalline water stabilized the hydrophilic layer of the hydrate more than that of the anhydrate. Furthermore, the geometry optimization of the dehydration model and the lattice energy calculations revealed that the conformational change during the dehydration process and the transition to the hydrate form in the solid phase are energetically induced.

Solvates are important forms of crystalline materials and their formation and desolvation would affect the quality of the final products. In this work, to better understand the desolvation mechanism of solvates and its effect on the properties of the final products, cefathiamidine was selected as the model compound to investigate the influence of intermolecular interactions and the crystal structure on the desolvation process. Three new solvates and one reported solvate of cefathiamidine, including acetonitrile solvate monohydrate S1, acetone solvate monohydrate S2, n-propanol solvate 1.5 hydrate S3 and isopropanol solvate S4, were obtained by solution crystallization and their structures were determined by single crystal X-ray diffraction. The results indicated that the cefathiamidine molecule is highly conformationally flexible and eight conformations were observed in these solvates. The different solvates exhibit different intermolecular interactions, packing patterns and crystal stabilities. Furthermore, the desolvation processes of the solvates were systematically investigated by various analytical techniques and were analyzed based on the intermolecular interactions, molecular networks, void types, proportion of voids and packing patterns. The results showed that the desolvation of solvates S1 and S2 followed a cooperative–reorganization mechanism while the desolvation of solvate S3 and solvate S4 followed a destruction–reconstruction mechanism and a destruction–collapse mechanism, respectively. Finally, the corresponding mechanisms of the different solvates were proposed.